Created by comedian Richard Herring, St Skeletor's Day falls on February 15th (the day after valentine's day) every year as a separate celebration for all the bitter lonely single people who didn't get cards the day before, or on any valentine's day ever.

Adam: Did you get any St Valentines Day cards?
Teela: No, I celebrate St Skeletor's day.
Adam: Did you get any St Skeletor's Day cards?
Teela: ...no.